Hanseniaspora uvarum and Hanseniaspora opuntiae differ in their growth and in the production of volatile organic compounds in wine

In recent years, Hanseniaspora uvarum has been partially replaced in Slovenian vineyards by the thermotolerant and invasive Hanseniaspora opuntiae. The fermentation capacity of both Hanseniaspora species was evaluated based on CO₂ release in synthetic and natural must. Additionally, co-inoculations of both strains with S. cerevisiae were carried out in Sauvignon Blanc must at different ratios (1:10 and 10:1). In all experiments, microbial populations were monitored, and the chemical and volatile profiles of the resulting wines were evaluated. During alcoholic fermentation (AF) with pure cultures, the fermentation kinetics of the two Hanseniaspora species were comparable, with CO₂ release in natural and synthetic must being two to five times lower compared to AF with the S. cerevisiae. In mixed AF with Hanseniaspora species and S. cerevisiae, there were no significant differences in fermentation capacity at the end of the fermentation compared to S. cerevisiae AF. However, the growth rate appears to be lower in H. opuntiae than in H. uvarum under oenological conditions. The results also showed that the formation of fermentation products differed between the two Hanseniaspora species in pure or mixed cultures, depending on the fermentation medium and inoculum ratio. H. opuntiae was a major producer of 2-phenylethyl acetate, and H. uvarum was a major producer of glycerol during alcoholic fermentation with natural must. The same tendency was observed for isoamyl acetate and ethyl acetate. We can conclude that H. opuntiae could become an important trigger for changes in wine composition if H. uvarum is further replaced on grape berries. KEY POINTS: • In mixed AF, there was no antagonism between Hanseniaspora and Saccharomyces strains • The concentrations of fermentation products differed between Hanseniaspora species. • H. opuntiae could influence changes in wine composition produced by non-inoculated AF.